Calcium Deficiency in Diet Decreases the Magnesium Content in Bone and Affects Femur Physicochemical Properties in Growing Rats.

This study evaluates the effect of three calcium levels in the diet (normal, moderate, and severe calcium depletion) on bone metabolism of male Wistar rats during their growth period. Bone mineral density (BMD) and femur length were determined in vivo during the growth stage using a single X-ray transmission system. The apparent calcium absorption was calculated in the rat adolescent and adulthood stages. At the end of the experiment, calcium concentrations in serum and urine were analyzed. The bones were evaluated postmortem to corroborate in vivo analyses. Microstructural properties of cortical and trabecular tissues of femurs bones were assessed using scanning electron microscopy. Bone mineral contents (Mg, Ca, P, and K) were quantified by inductively coupled plasma. Severe calcium depletion in the diets in the development stage affects the bone quality parameters such as bone mineral density and mineral content. Moreover, it was found thinner cortical and trabecular bone areas. Additionally, it was found that severe calcium depletion increased the apparent absorption of calcium as a defense mechanism, but with the decrease of the BMD peak, and the thickness of cortical bone as well as trabecular bone porosity. The severe calcium depletion increased the efficiency of apparent absorption calcium as a defense mechanism, but, even so, decreases the BMD peak as well as the thickness of cortical bone and trabecular bone porosity.

Effect of the addition of potassium and magnesium ions on the thermal, pasting, and functional properties of plantain starch (Musa paradisiaca).

Starch is a biopolymer widely used in the industry; however, rarely used in its native form, making necessary its modification. This work studied the effect of the inclusion of potassium and magnesium ions on the physicochemical properties of plantain starch. Ionic solutions were prepared at five concentrations between 0.0 and 0.3 M. The gelatinization, thermal degradation, viscosity, swelling power, morphological and structural changes were studied. Results showed that ion addition increased the swelling and solubility index. Both ions affected the gelatinization temperature; shift in characteristic temperatures was observed. The more significant change in the viscosity profile was showed in the final region; both ions permitted the re-ordering of the polymeric chains, but magnesium showed a greater trend towards viscosity recovery. In the thermogravimetric analysis, a lower degradation temperature was observed for starch added with ions. Structural analysis showed that for higher concentrations of potassium the addition was not carried out and crystallographic phase potassium chloride appears in the diffractogram. All the results showed that the ions inclusion produced changes in the physicochemical properties on starch, but magnesium had a greater effect on its polymeric matrix according to infrared spectroscopy, which could be due to its high electronegativity and low molecular weight.

Physicochemical, morphological, and rheological characterization of Xanthosoma robustum Lego-like starch.

This work presents the physicochemical and pasting characterization of isolated mafafa starch and mafafa flour (Xanthosoma robustum). According to SEM images of mafafa starches in the tuber, these starches form Lego-like shaped structures with diameters between 8 and 35 µm conformed by several starch granules of wedge shape that range from 2 to 7 µm. The isolated mafafa starch is characterized by its low contents of protein, fat, and ash. The starch content in isolated starch was found to be 88.58% while the amylose content obtained was 35.43%. X-ray diffraction studies confirm that isolated starch is composed mainly by amylopectin. These results were confirmed by differential scanning calorimetry and thermo gravimetric analysis. This is the first report of the molecular parameters for mafafa starch: molar mass that ranged between 2×10(8) and 4×10(8) g/mol, size (Rg) value between 279 and 295 nm, and molecular density value between 9.2 and 9.7 g/(mol nm(3)). This study indicates that mafafa starch shows long chains of amylopectin this fact contributes to higher viscosity development and higher gel stability. The obtained gel phase is transparent in the UV-vis region. The viscosity, gel stability and optical properties suggest that there is potential for mafafa starch applications in the food industry.